Jeez, that is a roundabout way of getting there, especially when NWA has nonstops EWR-AMS. Anyway, it will be an NWA 747-400 - NWA68 is the flight number. Yes, definitely ask the purser - especially if you board early, they may even get you up there before you depart. I have ridden jumpseat many, many times across the Atlantic, and I have seen several people allowed up front before departure over the years. Make sure you show your licence to the purser.